Apple announced that iTunes had become the number 2 music retailer in the U.S., behind only Wal-Mart.

“We’d like to thank the over 50 million music lovers who have helped the iTunes Store reach this incredible milestone,” said Eddy Cue, Apple’s vice president of iTunes. “We continue to add great new features like iTunes Movie Rentals to give our customers even more reason to love iTunes.”

The rankings are based on NPD Group’s MusicWatch data. iTunes has sold over four billion songs, with 20 million songs sold on Christmas Day 2007 alone. iTunes has overtaken Best Buy which previously occupied the #2 spot.

Keep in mind what a change this is. The second largest seller of music in this country is a computer company. A company that many people refer to as still having an insignificant market share. My purpose here is not blowing them up as a computer seller my point here is to highlight how much this entire market has changed in a very short time and what an different direction it went. The markets are changing much faster than the brick and mortar stores and most hardware makers are.

Thinking ahead of your customers means you’re ahead of the market, considerably. Thinking in time with the market means you’re, at best, a little behind. Thinking that what worked last year will work this year and even result increases over last year is dangerous, at best.